Malaysia Airlines flight MH370 did not climb to 13,700m then dive below 7,000m before it vanished, international investigators said, contradicting earlier reports based on Malaysia’s military radar data.

The New York Times reported today investigators discovered the jet had not soared and swooped as they believed earlier, but remained in controlled flight for hours after contact was lost, until it ran out of fuel over the southern Indian Ocean.

It said they concluded this after a re-examination of the military radar data and the pings the aircraft exchanged with an Inmarsat satellite over the Equator showed that the radar’s altitude readings? appeared to be incorrect.

An international review found Malaysia’s radar equipment had not been calibrated with enough precision for the readings to be accurate, the NYT said.

While many military radar can detect altitude and give accurate readings of an aircraft’s location, speed and direction, the equipment must be recalibrated regularly and carefully according to local atmospheric conditions, it said.

“The primary radar data pertaining to altitude is regarded as unreliable,” Angus Houston, the head of the Joint Agency Coordination Centre, was quoted as saying.

The radar tracked MH370 as it veered off its scheduled flight path over the Gulf of Thailand and flew west across the peninsula and Strait of Malacca.

The ?plane then passed beyond the radar’s range near the northern tip of the Indonesian island of Sumatra.

The radar readings suggested the plane soared above its certified maximum altitude of 13,700m, then dipped low over the ranges of Malaysia, before climbing back to 7,000m or higher over the Strait of Malacca.

But Houston told the NYT that he doubted whether anyone could prove the plane had soared and swooped the way initial reports suggested.

“There’s nothing reliable about height,” Martin Dolan, the chief commissioner of the Australian Transport Safety Bureau, was quoted as saying in the report.

The report said dismissal of the radar altitude data prompted a change in the focus of the search, as the plane’s fuel would have lasted longer if it maintained a steadier altitude.

Data from the pings, or the electronic handshakes, led investigators to conclude that the aircraft came down in the ocean west of Australia along what is called the seventh arc, the area of the final handshake with the plane.

“Everyone agrees that is where the aircraft ran out of fuel,” said Dolan in the report.

Officials said the search would now move hundreds of kilometres southwest across the arc, after the Australian government had scoured the northeast end based on the conclusion that the jet had burned a great deal of fuel.

The New York Times said the specifics were still being finalised, but the new search zone was likely to be an area about 640km long and some 97km wide.

This was based on the assumption that the plane was being flown by its? autopilot, which was unable to control the plane when the engine stopped and would have caused the plane to stall and fall into the ocean.